Plk4 and Aurora A cooperate in the initiation of acentriolar spindle assembly in mammalian oocytes

Establishing the bipolar spindle in mammalian oocytes after their prolonged arrest is crucial for meiotic fidelity and subsequent development. In contrast to somatic cells, the first meiotic spindle assembles in the absence of centriole-containing centrosomes. Ran-GTP can promote microtubule nucleation near chromatin, but additional unidentified factors are postulated for the activity of multiple acentriolar microtubule organizing centers in the oocyte. We now demonstrate that partially overlapping, nonredundant functions of Aurora A and Plk4 kinases contribute to initiate acentriolar meiosis I spindle formation. Loss of microtubule nucleation after simultaneous chemical inhibition of both kinases can be significantly rescued by drug-resistant Aurora A alone. Drug-resistant Plk4 can enhance Aurora A–mediated rescue, and, accordingly, Plk4 can phosphorylate and potentiate the activity of Aurora A in vitro. Both kinases function distinctly from Ran, which amplifies microtubule growth. We conclude that Aurora A and Plk4 are rate-limiting factors contributing to microtubule growth as the acentriolar oocyte resumes meiosis.L. Bury was the recipient of a Cancer Research UK research studentship from Cambridge Cancer Centre. P.A. Coelho is supported by Cancer Research UK program grant C3/A18795 to D.M. Glover. M. Zernicka-Goetz is a Wellcome Trust Senior Fellow. P.A. Eyers acknowledges North West Cancer Research for additional support (grants CR1037 and CR1088)

Predicting Passive Permeability of Drug-like Molecules from Chemical Structure: Where Are We?

Intestinal absorption in human is routinely predicted in drug discovery using <i>in vitro</i> assays such as permeability in the Madin-Darby canine kidney cell line. <i>In silico</i> models trained on these data are used in drug discovery efforts to prioritize novel chemical targets for synthesis; however, their proprietary nature and the limited validation available, which is usually restricted to predicting <i>in vitro</i> permeability, are barriers to widespread adoption. Because of the categorical nature of the <i>in vitro</i> permeability assay, intrinsic assay variability, and the challenges often encountered when translating <i>in vitro</i> data to an <i>in vivo</i> drug property, validation based solely on <i>in vitro</i> data might not be a good characterization of the usefulness of the <i>in silico</i> tool. In this work, we analyze the performance of three different <i>in silico</i> models in predicting the <i>in vitro</i> and <i>in vivo</i> permeability of 300 marketed drugs and 86 discovery compounds. The models differ in their approach (mechanistic vs quantitative structure–activity relationship) and the degree of complexity; one of them is a linear equation based on seven simple physicochemical descriptors and is presented for the first time in this work. Results show that <i>in silico</i> models can be successfully used to complement the discovery toolbox for characterizing <i>in vivo</i> intestinal permeability, defined using fraction of dose absorbed in human (Fa) and human jejunal permeability (<i>P</i>_eff). While the <i>in vitro</i> permeability models outperformed the <i>in silico</i> approach at predicting each of the <i>in vivo</i> end points explored, the gap in predictivity between the <i>in vitro</i> and the <i>in vivo</i> data was generally comparable to the gap between <i>in silico</i> and <i>in vitro</i> data. The <i>in vitro</i> and <i>in silico</i> approaches shared many of the same outliers, which can often be explained by the route of drug absorption (paracellular vs transcellular, active vs passive). Data suggest that the discovery process can greatly benefit from an early adoption of <i>in silico</i> models for predicting permeability as well as from a careful analysis of the <i>in silico</i> to <i>in vivo</i> disconnects

Immigrant students and the ecology of externalization in a secondary school in Spain

We examine how counselors, teachers, and other professionals at a secondary school in Madrid (Spain) understand cultural diversity and work with immigrant students' educational circumstances. Our analysis suggests that cultural diversity is largely construed as a problem and the explanation of educational difficulties is organized around an "externalizing logic" in which responsibility for educational outcomes is transferred to process and programs outside "ordinary" teachers' realm of action. We analyze these discourses and institutional practices from an ecological perspective: within the context of the local changing demographics of the school, regional/national policy measures around diversity, and wider conceptualizations of cultural diversity in Spain's education system

Structure-Guided Design of Group I Selective p21-Activated Kinase Inhibitors

The p21-activated kinases (PAKs) play important roles in cytoskeletal organization, cellular morphogenesis, and survival and have generated significant attention as potential therapeutic targets for cancer. Following a high-throughput screen, we identified an aminopyrazole scaffold-based series that was optimized to yield group I selective PAK inhibitors. A structure-based design effort aimed at targeting the ribose pocket for both potency and selectivity led to much-improved group I vs II selectivity. Early lead compounds contained a basic primary amine, which was found to be a major metabolic soft spot with in vivo clearance proceeding predominantly via <i>N</i>-acetylation. We succeeded in identifying replacements with improved metabolic stability, leading to compounds with lower in vivo rodent clearance and excellent group I PAK selectivity

Data from: Vascular disease in COPD: systemic and pulmonary expression of PARC (Pulmonary and Activation-Regulated Chemokine)

Introduction. The role of Pulmonary and Activation-Regulated Chemokine (PARC) in the physiopathology of Chronic Obstructive Pulmonary Disease (COPD) is not fully understood. The aim of the present study is to analyze the expression of PARC in lung tissue and its relationship with the vascular remodeling of the systemic and pulmonary arteries of COPD subjects. Methods. To achieve this objective, protein and gene expression experiments, together with ELISA assays, were performed on the lung tissue, intercostal arteries and serum samples from COPD patients, non-obstructed smokers (NOS) and never-smokers (NS). Results. A total of 57 subjects were included in the analysis (23 COPD, 18 NOS and 16 NS). In the comparisons between groups, a significantly increased lung protein expression of PARC was observed in the COPD group compared to the NOS group (1.96±0.22 vs. 1.29±0.27, P-adjusted=0.038). PARC was located predominantly in the smooth muscle cells of the remodeled pulmonary muscular arteries and the macrophage-rich area of the alveolar parenchyma. No differences were detected in PARC gene expression analyses. The protein content of PARC in the intercostal arteries were similar between groups, though little remodeling was observed in these arteries. Circulating levels of PARC were numerically higher in patients with COPD compared to NOS and NS. Conclusion. The results of the present study suggest an increased lung protein expression of PARC in COPD subjects. This protein was mainly localized in the smooth muscle cells of the pulmonary muscular arteries and was associated with the severity of intimal thickening, indicating its possible role in this remodeling process